1. Two rapid, simple (requiring minimal pre-sample preparation), sensitive, and specific assay systems for tocopherols (vitamin E) in small samples of vertebrate and invertebrate tissues -- a rotifer bioassay and spectrofluorometry -- will be improved and analyzed by determining: a) the response of the bioassay to tocols, tocotrienols, and related compounds; and b) the applicability of the bioassay and spectrofluorometry for measurement of vitamin E in lipid mixtures and crude lipid fractions. 2. Rotifer bioassays and spectrofluorometric assays will be used for direct measurements of tocopherol in affected tissues and organs in vitamin E-deficient animals and will be related directly to structural changes observed at the light and electron microscope levels. 3. Tocopherol requirements and effects in selected invertebrates will be determined using tocopherol-deficient and supplemented diets. 4. The contents and roles of tocopherol and other fat-soluble vitamins in surface and deep-sea fishes will be investigated to determine whether fat-soluble vitamin deficiences may occur in organisms naturally remote from the sources of these vitamins. Animals and typical samples of available food material will be obtained by trawling at different ocean depths down to about 5000 meters, and their contents of fat-soluble vitamins will be analyzed by various bioassay and physicochemical methods. 5. An uknown, probably new vitamin E compound, present in plants both after cutting and senescence, will be purified and identified. The relative biopotency of this compound will be determined in the rat gestation-resorption assay, and information on the derivation and stability of the compound will be obtained.